Cells of human monocyte-line U_(937)and human T-lymphocyte-line HSB_2 inoculated withHSV-1 were studied by observing the dynamics of virus titer,cellular proliferation and cy-topathogenic effect,expression of virus antigen and existing time of virus DNA. The resultsshowed that after inoculation,U_(937) cells allowed the virus to replicate only to a quite low de-gree and only for a quite short period.Twelve days after inoculation the virus was not de-tectable in the supernatans. After proliferation inhibltion and death for about 2 weeks , thecells were gradually recovered;stimulation of U(937)cells with LPS increased the virus infectiv-ity ,prolonged the infection period and promoted the formation of temporary persistent infec-tion.The results also showed that HSB_2 cells permited the virus to replicate to a higher titer,and presented an acute and cytocidal infection; stimulation of HSB_2 cells with PHA did notalter the character of the infection of the cells.